1. Field of the Invention
The present invention relates to a golf club and a method for manufacturing the same.
2. Description of the Related Art
As conventional known techniques of joining a metallic shell and a fiber-reinforced-plastic-made shell in order to form a head body employing a hollow structure, Japanese Unexamined Patent Publication No. 2003-205055 discloses ones that: bonding a joining portion of the fiber-reinforced-plastic-made shell to both surfaces of a joining portion of the metallic shell; or forming a through-hole on the joining portion of the metallic shell so as to obtain joining strength of the metallic shell relative to the fiber-reinforced-plastic-made shell.
According to those conventional techniques, the golf club head can be lightened by the fiber-reinforced-plastic-made shell. In this golf club head, however, there is a limitation of enhancing its strength even the fiber-reinforced-plastic-made shell is used.
As a technique to solve this problem, one can be considered that forming the golf club head by combining a plurality of metals, each metal having small specific weight and different strength. According to this technique, for example, pure titanium/titanium alloy and magnesium alloy each having small specific gravity are used. Pure titanium/titanium alloy is used for a portion of the golf club head where larger durability and strength are required, while magnesium ally is used for a portion of the golf club head where smaller durability and strength are required.
However, welding the different kinds of metals in order to join them is difficult. Moreover, large adhesion can not be obtained when the different kinds of metals are joined by bonding as the above-described conventional techniques, or even an opening are provided thereon for bonding. Accordingly, sufficient joining strength of the different kinds of metals can not be obtained.